Perhaps the most desirable attribute which copper alloys may possess is a combination of high strength and high electrical conductivity. Increases in electrical conductivity in an alloy are often brought about by precipitation of alloying element or elements from solid solution. This precipitation usually helps to increase the strength of the alloy but only up to a point. The precipitation heat treatment of the alloy which imparts maximum strength to the alloy is usually not the same as the precipitation treatment which imparts maximum electrical conductivity. For a given aging temperature, maximum electrical conductivity occurs at longer aging times than does maximum strength.
Zirconium and chromium are well-known additions to copper alloys for providing desirable high strength combined with high electrical conductivity. Commercial copper-chromium and copper-zirconium alloys are available, and copper-chromium-zirconium alloys are also known. Precipitation of chromium in copper is known to give large increases in strength and electrical conductivity over the values for the solid solution. The resultant precipitation hardened alloys have lower electrical conductivity but significantly higher strength than pure copper. Precipitation of zirconium in copper is known to give large increases in electrical conductivity but only small increases in strength over the values for the solid solution. Zirconium also significantly raises the recrystallization temperature of copper. The resultant alloys have lower conductivity than copper but a much better resistance to softening at high temperatures.
Russian Pat. No. 185,068 discloses copper base alloys that contain chromium, zirconium and vanadium. The patent does not teach any processing steps for this alloy combination.
It is a principal object of the present invention to provide a process which is capable of improving both the strength and electrical conductivity of copper base alloys.
It is a further object of the present invention to provide a process as aforesaid which is relatively simple and convenient to use on a commercial scale.
Further objects and advantages of the present invention will appear hereinafter.